Because it is embodied in proteins, our biochemical realization of
inference violates several dichotomies that are present in the
abstract computational characterization of inference (level 1). Specifically, in our
realization, there is no hard boundary
between environment versus cell, or between inference versus action. This can be framed along the lines of Maturana and Varela
[1]}, who conceive of organisms as structurally coupled to their
environment. Perturbations generated outside the cell can push the cell's internal
state, while cells in turn shape the environment. This view does not
commit to sharp boundaries between an “external” environment and the
organism, or between the cell's perception of the environment and
the “real” state of the environment. To borrow from Merleau-Ponty [2]}, the
environment awakens an echo in the cellular body, in our case through
the production of memory molecules (whose concentrations encode
probabilities that can be read out to realize inference). The circuit
we have presented in turn consumes the very signal that awakens the
echo, therefore shaping the environment and its perception. This picture is also inherently
dynamic: as long as the cell does not disintegrate, the structural
coupling between cell and environment continues and there is no need to invoke
steady-states (Fig. REF ).As Maturana and Varela put it: “Ontogeny is
the history of structural change in a unity without loss of
organization in that unity. This ongoing structural change occurs in
the unity from moment to moment, either as a change triggered by
interactions coming from the environment in which it exists or as a
result of its internal dynamics. As regards its continuous
interactions with the environment, the cell unity classifies them
and sees them in accordance with its structure at every
instant. That structure, in turn, continuously changes because of
its internal dynamics. The overall result is that the ontogenic
transformation of a unity ceases only with its disintegration.”
[1]} This way of viewing cells
(and organisms) in relation to their environment is rooted in
approaches to cognition that emphasize embodied or enacted
perspectives (which have been applied to questions spanning artificial
intelligence, psychology, and biology [4]}, [1]}, [6]}, [7]}).
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